1. Field of the Invention
The present invention relates generally to structures and assemblies for use in connection with a patient interface device, such as a respiratory mask, and a mask attachment assembly, such as a headgear having straps to retain the mask in a sealed position on a user's face and, in particular, to a mask attachment assembly for connection to the respiratory mask and providing attachable and releasable straps, thereby providing additional convenience, ease-of-use, ease-of-adjustment and removal and improved comfort to the patient.
2. Description of the Related Art
It is well known to treat a medical disorder or to diagnose, treat or monitor the condition of the patient using medical equipment. For example, a patient may be monitored and treated for various sleep disorders in a lab or in some other setting. An example of a type of sleep disorder is sleep apnea. Obstructive sleep apnea is characterized by a collapse of the upper airways during sleep, while central sleep apnea is characterized by the suspension of all respiratory movement. Obstructive sleep apnea and central sleep apnea may be combined in a condition referred to as mixed apnea.
In order to diagnose and/or treat such medical disorders, various equipment and devices are required for successful diagnosis and a resulting prescribed treatment. Further, there are numerous situations where it is necessary or desirable to deliver a flow of breathing gas, non-invasively, to the airway of a patient, i.e., without intubating the patient or surgically inserting a tracheotomy tube in their trachea. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation. It is also known to deliver continuous positive airway pressure (CPAP) or variable airway pressure, which varies with the patient's respiratory cycle or a monitored condition of the patient, to treat a medical disorder, such as sleep apnea syndrome, in particular, obstructive sleep apnea (OSA), congestive heart failure, stroke, Cheynes-Stokes respiration, etc. Non-invasive ventilation and pressure support therapies involve the placement of a patient interface device, which is typically a nasal or nasal/oral mask, on the face of a patient to interface the ventilator or pressure support device with the airway of the patient, so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient.
Patients suffering from a pulmonary or respiratory disorder, such as obstructive sleep apnea, are often treated with a pressure support device, such as a continuous positive airway pressure (CPAP) device. A CPAP device delivers a flow of fluid to the airway of the patient throughout the patient's breathing cycle in order to “splint” the airway open, thereby preventing its collapse during sleep. In another type of treatment, bi-level positive pressure therapy is provided to the patient, in which the pressure of air delivered to the patient's airway varies or is synchronized with the patient's breathing cycle to maximize therapeutic effect and comfort to the patient. A pressure support device may also provide “bi-level” pressure support, in which a lower pressure is delivered to the patient during the patient's expiratory phase then during the inspiratory phase.
It is also known to provide an auto-titration positive pressure therapy in which the pressure provided to the patient changes based upon the detected conditions of the patient, such as whether the patient is snoring or experiencing an apnea, hypopnea, or upper airway resistance. Such a device adjusts the pressure delivered to the patient, based on whether or not the patient is snoring. For example, a pressure support device may actively test the patient's airway to determine whether obstruction, complete or partial, could occur and adjust the pressure output to avoid this result.
Other modes of providing positive pressure support to a patient are known. For example, a proportional assist ventilation mode of pressure support provides a positive pressure therapy in which the pressure of gas delivered to the patient varies with the patient's breathing effort to increase the comfort of the patient. Proportional positive airway pressure (PPAP) devices deliver breathing gas to the patient based on the flow generated by the patient.
For purposes of the present invention, the phrase “pressure support system”, “pressure support device”, or “positive pressure support” includes any medical device or method that delivers a flow of breathing gas to the airway of a patient, including a ventilator, CPAP, bi-level, PAV, PPAP, or bi-level pressure support system.
Typically, gas such as oxygen or air is delivered by a pressure generating device, which may be, in turn, in fluid communication with an oxygen tank. The oxygen flows from the source through the regulator devices, through the pressure generating device and further through a conduit into a patient interface. The pressure generating device and the conduit, such as a gas hose, are considered the patient circuit, such that a coupling assembly is required for connecting the patient circuit to the patient interface device.
In a conventional pressure support system, a flexible conduit is coupled to an exit conduit from the pressure generating device. The flexible conduit forms part of the patient circuit that carries the flow of breathing gas from the pressure generating system to the patient interface device. In a support system, the patient interface device connects the patient circuit with the airway of the patient so that the elevated pressure gas flow is delivered to the patient's airway.
In order to provide gas or, as discussed above, oxygen to a patient, the patient must use a patient interface device, such as a nasal mask (including external cushions and/or internal prongs), nasal/oral mask, full-face mask, nasal cannula, oral mouthpiece, tracheal tube, endotracheal tube, or hood. Typically, patient interface devices include a mask shell having a cushion attached to the shell that contacts the surface of the patient. The mask shell and cushion are held in place by a headgear that wraps around the head of the patient. Together, the mask and headgear form the patient interface assembly. A typical mask attachment assembly includes headgear having flexible, adjustable straps that extend from the mask to attach the mask to the patient. Other techniques for attaching a patient interface device use a vice-like device that anchors at the front and back of the patient's head to support the mask on the user. See, e.g., U.S. Pat. No. 6,516,802.
Because such patient interface devices are typically worn for an extended period of time, a variety of concerns must be taken into consideration. For example, in providing CPAP or other positive pressure therapy to treat OSA, the patient normally wears the patient interface device all night long while he or she sleeps. In order to be successful in these applications, a patient interface device needs to consider two, often competing, goals: comfort and technical effectiveness. Failure to achieve either goal is likely to result in low efficacy. A comfortable, but technically ineffective, patient interface device may achieve superior patient compliance; however, its technical ineffectiveness will minimize the therapeutic benefit achieved. Alternatively, a technically effective, but uncomfortable, patient interface may be capable of treating a patient; yet, the lack of comfort often results in low patient compliance. Low patient compliance also undermines the therapeutic benefit ultimately obtained by the patient. Thus, further advancements for interfacing a pressure support system to the airway of a patient are desired.
It is known to maintain such interface devices on the face of a wearer by a headgear having upper and lower straps, each having opposite ends threaded through connecting elements provided on the opposite sides and top of the interface device, such as a mask. Because such masks are typically worn for an extended period of time, it is important that the headgear maintain the mask tight enough to seal against a patient's face without discomfort. Adjustability of the mask and/or the headgear, together with increased patient comfort, is paramount. However, most important is the maintenance of the seal between the mask and the user's face. According to the prior art, various headgear have been developed that position the straps in various locations with respect to the mask in order to effect this seal.
According to the prior art, a variety of mask attachment assemblies, headgear, straps and the like are disclosed and used for maintaining engagement between the mask and the user's face. For example, one such a headgear is discussed in U.S. Pat. No. 6,662,803 to Graden et al. As best illustrated in FIG. 2 of the Graden patent, a mask is held against the user's face using a headgear, which is secured around the back of the user's head. The positioning and use of multiple straps of the headgear in connection with the mask and the forehead member provide the compressive force to effect the required seal.
Another prior art headgear assembly is disclosed in U.S. Pat. No. 6,805,117 to Ho et al. This reference teaches an adjustable headgear with a front adjustment strap attached to a portion of a headpiece and extending past each side of the headpiece, which defines front adjustment strap portions. A rear joint piece is attached to a central portion of the rear edge portion at an upper edge, such that the rear joint piece is positionable along the lower portion of the patient's head. Rear adjustment straps are attached to upper tabs, and each rear adjustment strap is further attached to a portion of the rear edge of the headpiece. The front adjustment straps and rear adjustment straps include some fastening system for adjustably and releasably connecting the strap end portions to each other. In this manner, an adjustable headgear is provided that fits and can be adjusted to fit differently sized patients.
Another such headgear is disclosed in U.S. Pat. No. 5,517,986 to Starr et al. In particular, the headgear of the Starr patent includes a headpiece adapted to fit the crown and back of a patient's head. As seen in FIG. 1 of the Starr patent, lower straps provide a two-point connection with a gas delivery mask. Depending straps depending from headpiece are connected to and moveable relative to the lower straps. Additionally, a pair of upper straps and can be used to provide a four-point connection with the gas delivery mask, if needed, as shown in FIG. 7 of the Starr patent.
While all of the above-referenced prior art headgear and mask attachment assemblies provide some adjustability and flexible positioning of the headgear or assembly, there is considerable room in the art for improved adjustability. Such additional and beneficial characteristics would allow the mask to fit a wider variety of patients, and would greatly improve the comfort provided to the patient wearing the headgear for an extended period of time. In addition, effective and quick attachment and detachment of the headgear or assembly, which engages and disengages the mask, provides a much more functional and user-friendly device.